Abstract Details

Title Age-Related Reduction of Differentiated Neural Responses to Different Stimulus Types

Topic Behavioral Neurology

Presentation(s) P07 - (-)

Poster/Presentation
Number 157

Objective

Background BACKGROUND: The dedifferentiation theory of cognitive aging stresses the failure of older adults to recruit specialized neural mechanisms, which has been viewed as being due to a common underlying process that uniformly disrupts all cognitive functions.

Design/Methods DESIGN/METHODS: ERPs were measured in 12 young (mean age 23), 14 middle-aged (mean age 51), 15 young-old (mean age 74), and 23 old-old (mean age 85) well-matched, cognitively high-performing adults. Subjects responded to rare visual target letters under low memory load (1 target letter) and high memory load (multiple target letters). The anterior P3a was used as an index of orienting/executive control, and the posterior P3b as an index of categorization/memory updating.

Results RESULTS: Groups did not differ in target accuracy. For both the P3a and P3b components, the difference in amplitude between targets and standards decreased substantially as a function of age. Advancing age predicted increasing size of the P3a to standards and decreasing size of the P3b to targets. The magnitude of these age-associated differences was similar under low and high load conditions.

Conclusions CONCLUSIONS: Cognitively high performing older adults generate increasingly less differentiated neural responses to target and standard stimuli. Changes in categorization/updating (P3b) seem to be driven by an age-related reduction in the response to targets, whereas changes in orienting/executive control (P3a) seem to be driven by an age-related increase in the response to standards. These results confirm an age-associated reduction in the brain's ability to differentially process different stimulus types. However, the mechanisms underlying this change vary across different cognitive operations. The diminished posterior P3b may reflect attenuation of the categorization process in response to targets, whereas the increased anterior P3a may represent compensatory frontal activity to carry out the task of distinguishing between standards and targets.

Authors/Disclosures
Kirk R. Daffner, MD, FAAN (Brigham & Women's Hospital - Harvard Medical School) PRESENTER	The institution of Dr. Daffner has received research support from Azheimer's Association. The institution of Dr. Daffner has received research support from FUJIFILM.
	No disclosure on file
Harald Hegen, MD	Dr. Hegen has nothing to disclose.
Brittany Alperin (Brigham and Women's Hospital)	No disclosure on file
Lisa Christopher-Stine, MD, MPH (Johns Hopkins University School of Medicine)	No disclosure on file
Tatyana Zhuravleva	No disclosure on file
	No disclosure on file
Dorene M. Rentz, PsyD (Brigham and Women's Hospital)	Dr. Rentz has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Digital Cognition Technologies. Dr. Rentz has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Neurotrack.

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